sulfuric acid; hydrogen bromide; copper(I) bromide; sodium nitrite 1) acetic acid, 18 grad, 1 h.; 2) 65 grad, 30 min. and room temp. 24 h; Yield given. Multistep reaction;

1: 1) sodium nitrite, sulfuric acid; 2) copper(I) oxide, ethanol / 1) acetic acid, 18 deg C, 1 h.; 2) 60 deg C, 80 min. 2: 52 percent / tin, conc. HCl / ethanol / 1 h / Heating View Scheme